What appears to be the role of NPPV for the long-term support of patients with severe "stable" COPD?

A. NPPV does not benefit patients with this condition.
B. Patients who benefit most from NPPV in this group are those who have greater hypercapnia and more nocturnal O2 desaturation.
C. Patients who benefit most from NPPV in this group are those who experience less hypercapnia and less nocturnal O2 desaturation.
D. The data obtained from this group of patients are inconclusive in terms of the efficacy of NPPV.

ANS: B (page 372)
Cognitive Level: Recall
A. Incorrect response: See explanation B.
B. Correct response: The long-term application of NPPV among severe "stable" COPD patients has been somewhat controversial. The substantial differences in baseline characteristics among patients entering these trials may explain the conflicting results. Patients who respond favorably had greater hypercapnia and more nocturnal O2 desaturation despite having less severe airway obstruction than patients responding unfavorably to NPPV. These data support the hypothesis that the subgroup of patients most likely to benefit from NPPV is that with substantial daytime CO2 retention (Paco2 >50 to 55 mm Hg) and nocturnal O2 desaturations.
C. Incorrect response: See explanation B.
D. Incorrect response: See explanation B.